Just like when the MacBook Pros went Core 2 Duo, the upgrade of Apple's MacBook line means the old leftover laptops get a bit of a discount. For example, the 1.83 GHz model that used to be $1099 is now $899, and the 2.0 GHz black model that used to be $1499 is now $1099. Quite a steep drop thanks to their newborn brothers pushing them out from under their mother's teat.
If you're in the mood for a 12-inch PowerBook, they still have refurbished models of those going for $1199 down from their old original price of $1699.
Refurb Store [Apple]